Treatment of textile materials for repellency to chemical warfare liquids



United States Patent Ofiice 3,%8,l25. Patented Dec. 11, 1962 3,068,125TREATMENT OF TEXTHLE MATERIALS FQR RE PELLENCY T CHEMECAL WARFARELIQUKDS Robert L. Ciayton, lira, New Urleans, La, and Leopold Loch,Louisville, Ky, assignors to the United States oi America as representedby the Secretary of the Army N0 Drawing. Filed June 24, 1957, Ser. No.667,713 in Claims. (Cl. 117-161) (Granted under Titie 35, US. Code(1952), sec. 266) The invention described herein may be manufactured andused by or for the Government of the United States of America forgovernmental purposes without the payment to us of any royalty thereon.

This invention relates to a process for impregnating textile materialswhich renders said materials resistant to penetration or wetting byliquid droplets of chemical warfare agents. This invention relatesparticularly to the single application treatment of such textilematerials with a composite preparation comprising as its essentialingredients, a chromi-nuclear complex of a fluorinated monocarboxylicacid and a water-insoluble vinyl-type polymer.

Pending patent applications Serial Nos. 667,717 and 667,719, filed onthe same day as this application, describe surface coatings resistant tochemical Warfare liquids and the procedures for applying such resistantfinishes to textile fabrics. The present invention differs significantlyfrom those described in the pending applications above. This differenceand the attendant advantages arise from the incorporation of the activeingredients in one composite mixture. The present invention allows forgreater simplicity of application of the repellent coating together withsuch non-obvious advantages as improved repellency and greatly improvedstability of the chrorni-nuclear complex in the impregnating composite.

The newer chemical warfare liquids, particularly those designated as theG-agents, penetrate and wet through untreated porous textile fabricssubstantially instantaneously regardless of the chemical composition,construction or Weave of the cloth. Numerous compositions and treatmentsfor coating textiie materials have been developed to render suchmaterials impermeable to water and similar polar liquids. Suchtreatments are, in gen oral, or no value in proofing textile materialsagainst chemical warfare liquid agents of the type mentioned above. TheG-series agents are polar liquids of low SUI? face tension and are goodsolvents for many other organic materials.

By the term G-agents or G-series agents we refer to those compoundsdesignated by the Chemical Corps, United States Army, as GB (isopropylmethylphosphonofluoridate), GF (cyclohexyl methylphosphonofluoridate),and GA (ethyl dimethylphosphoroamido cyanidate).

According to the procedures described in the present invention, textilefabrics may be rendered nearly impermeable to the passage of liquiddroplets of chemical warfare agents while at the same time the textileafter treatments according to these procedures, exhibits air andwater-vapor permeability greater than that of the orginal fabric.

A primary objective of this invention is to provide a simple, singleapplication process for the treatment of textile fabrics which willresist penetration and wetting by the highly active chemical warfareagents and in particular will be resistant to the agent designated asstabilized GB for at least 1-2 hours, and which produces a fabric havingsuch textile properties as air permeability, softness, and tearresistance substantially as desirable as the untreated fabric. Anotherobject is to provide a repellency treatment and impregnation techniquesof such simplicity that they may be practiced as a bucket-typeimpregnation for use in the field without the employment of any controlor usual textile processing apparatus, and requiring no cure at elevatedtemperatures after impregnation. Another obiect is to provide aprocedure for producing a stable, free-flowing, iiuid composite mixtureof a chromi-nuclear complex, in which the acido group consistsessentially of a perfluoroalkanoyl or w-mono hydrofiuoroallranoyl groupcontaining 4 to 18 carbon atoms, and a Water-insoluble vinyl-typepolymeric material. Still another object is to provide a process forbonding Werner-type chromi-nuclear complexes of perfluoroormonohydrofiuoro-monocarboxyiic acids to acid sensitive materials,without causing undue degradation induced by the acid.

In general, in accordance with the present invention, a textile materialis rendered resistant to penetration or wetting by liquid chemicalWarfare agents by: impregnating the textile in an aqueous dispersioncontaining in admixture l240% of a water-insoluble resin of thevinylpolymer type and 0.6 to 3.0% of a chromi-nuclear complex, the acidogroup of which is either a perfluoroalkanoyl or amonohydrofiuoroalkanoyl group to a dry pick-up of from about 25-70percent by weight. In order to prevent coagulation on addition of thehighly acid :chromi-nuclear complex, it is necessary that thevinylpolymer type emulsion possess considerable acid tolerance. Goodstability of the composite emulsion has been obtained only withnon-ionic, electrically neutral emulsifiers, such as alkylphenylpolyethyleneglycol ethers, polyethyleneglycol alkyl ethers, alkyl arylpolyester alcohols, and polyoxyethylene lauryl alcohol. Suitablepolymers in the form of non-ionic aqueous emulsions, are included in thegroup consisting of polymers derived from lower alkylesters of acrylicacid and esters of vinyl alcohol with the lower carboxylic acids.Although stable composite emulsions may be prepared with chromi-nuclearcomplexes having acido groups containing two or more carbon atoms in thefluoroalkanoyl group, only those complexes in which the acido groupconsists of fluoroalkanoyl groups containing at least 4 carbon atomsgive the desired repellency. Curing of the impregnated fabric may beaccomplished immediately at temperatures from about to C. for from about30 to 90 minutes or preferably the wet impregnated fabric may be curedas above after first allowing to air-dry at temperatures from 20- 40 C.Significant, though in some cases slightly reduced, repellency may beobtained by merely air drying at temperatures from about 2040 C. withoutcuring at an elevated temperature.

Substantially any textile material composed of vegetable, animal,synthetic, or glass fibers may be employed. The employment of fabricscomposed essentially of cellulose textile fibers is preferred. Theinvention is especially adapted for the treatment of cotton clothingfabrics such as cotton sateen and the like.

The polymer dispersion can contain the amounts and types of emulsifying,wetting, and/or dispersing agents Darexes.

aces,

that are usually employed in polymer compositions adapted for productionof surface coatings with the restriction that any such additives shouldnot be so sensitive to acid as to cause coagulation, precipitation, orseparation of the emulsion on addition of the chromi-nuclear complex.The polymeric constituent of the treating composite can vary widely inmolecular weight or degree of polymerization. Illustrative exampleswhich are commercially available include film-forming dispersions ofpolyalkyl acrylates and polyvinyl acetates which are available under thetrade names Rhoplexes, Polycos, and Dispersions of polyethyl acrylateprepared by emulsion polymerization with a non-ionic emulsifier havealso proved satisfactory.

The Werner-type chromi-nuclear complexes in which the acido groupconsists essentially of perfiuoroalltanoyl groups are known compounds.Processes of producing them are described in US. Patent No. 2,662,835,and British Patent No. 712,784. These complexes are theperfiuoroalkanoyl analogs of the complexes described in US. Patent Nos.2,373,040 and 2,544,666. They can be produced and applied by proceduresdescribed in the patents cited above. In general, the perfiuoroalkanoylchromi-nuclear complexes can be prepared by effecting contact insolution between the perfiuoroalkanoic acid and a basic trivalentchromium salt of a monobasic acid, which salt has a basicity less than50%. The complexes can be dissolved in organic solvents such asisopropanol and the like alcohols. Illustrative examples of acidssuitable for employment as the acido group in the complexes include:perfiuorohexanoic, perfluoro-octanoic, perfluorodecanoic and the likeacids, as well as w-monohydrofiuoroalkanoic acids of the type H(CF),,COOH, in Which the hydrogen atom is on the terminal carbon atom and nhas even integral values between 4 and 18, inclusive. The complexes inwhich the acido groups consists essentially of perfiuoroalkanoyl groupscontaining 8-10 carbon atoms is preferred.

In preparing the composite emulsion for impregnating the textilematerial, the chromi-nuclear complex, usually prepared or obtained as a30-40% solution in isopropanol, is partially diluted with water to givean aqueous solution containing from about 1 to percent by weight of thesolid complex. The aqueous solution of the chrominuclear complex isadded slowly and with good stirring to the aqueous dispersion of thevinyl type polymer containing 12 to 60% of the polymer solids.

impregnation of the textile material may be accomplished substantiallyimmediately after mixing of the composite emulsion or preferzbly thecomposite emulsion may be aged for several days prior to employment as arepellency treatment for the textile material.

We have found that the repellency imparted to the textile material isgreatly enhanced by the aging process, and it is postulated that duringthis aging process there is a progressive adsorption of thechromi-nuclear complex molecules onto the surface of the dispersedpolymer particles and that this adsorption occurs in such manner thatthe polar end of the complex molecules containing the chromium atoms areaffixed to the surface of the polymer particles with theperfiuoroallranoyl groups extending outward from each polymer particleto form an outer layer consisting essentially of chains of carbon atomssurrounded by fluorine atoms. While the practice of this invention isnot premised upon any particular theory or postulated mechanism, it hasbeen definitely shown that the repellency imparted to the fabric isgreatly improved if the composite emulsion is allowed to age for 3 to 5days prior to impregnation and that this improvement appliesparticularly to the repellency obtained on the fabric not cured at anelevated temperature. It has further been found that this aging processcan be accelerated by mild heating of the composite emulsion attemperatures from about 40 to 80 C. for periods of time from about 5 to4 180 minutes, or by preheating the diluted aqueous solution of thechromi-nuclear complex prior to admixture with the polymeric resin.

The textile material can be impregnated with the composite emulsion bymeans of the usual procedures and apparatus for liquid impregnation oftextile materials, employing padders, centrifuges, squeeze rolls, andthe like. In the field the impregnation can be accomplished by a simplehand dipping and squeezing employing a dispersion concentration andsqueezing procedure found by experiment to produce the proper pick-up.The impregnation of the textile fabric to a dry pick-up of from about25-50 percent by weight is preferred.

The following examples are illustrative of the details of at least onemethod of practicing this invention; although testing is reported onlywith liquid GB, the successful repellency treatments for GB have beenfound as shown, for example, by the applications identified earlier inthis application, so outstandingly successful for the other chemicalwarfare agents, such as GA, HD, (2,2'dichlorodiethyl sulfide) andHN-3(2,2,2" trichlorotriethylamine) that further testing with thoseagents is not required.

As used in this specification, the terms wetting time" and penetrationtime have the following meanings. Wetting time is the time required fora drop of liquid, placed on the upper side of the fabric, to dissipate,i.e. to completely lose its identity as a drop. Penetration time is thetime required for the underside of the fabric to show the first trace ofpenetration by a drop of liquid placed on its upper side.

Example I I Repelleney to dro lots or Weight Weight Stabilized (i 13Emulslon No. ercent percent C404 Rhoplex FRN Penetration Wetting me time(1 second) (30 seconds) Both resistance to penetration and wettingthrough increase very markedly with increasing resin concentration Inthe treating composite and also with increasing concentration of thechromi-nuclear complex, although the improvement with the latter is lessnotable.

Example 2 Swatches of 8.5 oz. cotton sateen were impregnated incomposite emulsions containing 32 weight percent of the commerciallyavailable polyacrylic ester emulsion (Rhoplex FRN) and varying amountsof the chrominuclear complex of perfiuoro-octauoic acid (PC-804),

The composition data for these emulsions and the impregnation data aresummarized in the table below:

. FC-804 Rhoplex Dry Emulsion No. solids, FRN Swatch pick-up, percentsolids, No. percent percent 0. A 44.6 1 6 {B 41.4 2 1.5 A 47.3 32.0 {E22 All of these swatches were cured for one hour at 110 C. and thentested with stabilized liquid 63.

Repcllency to Stabilized GB Porosity Tenderization Emulsion Swatch No.No.

Penetra- Wetting t-ion time, time seconds seconds 6, 3 0 14,000 in an 88}Fair Slight.

9, 00 27,0 11,000 14,000 }Poor Greatest.

In consideration of both repellency and physical properties of thetreated sateen, a composite emulsion corresponding to the composition ofEmulsion #1 above is a preferred treatment for cotton sateen.

In order to demonstrate the beneficial effect of aging of the compositeemulsions and to demonstrate the high stability of chromi-nuclearcomplex, Emulsion #1 above was stored at room temperature for a periodof 18 days and used at various intervals during this time to treatswatches of cotton sateen.

It is apparent that incorporation of the chromi-nuclear complex in thenon-ionic emulsion imparts a much higher order of stability to thecomplex than is possible in aqueous solutions of the complex.

As a further example of the beneficial eiiects of aging of the compositeemulsion on repellency, samples of 8.5 02. cotton sateen were treated onconsecutive days in an impregnation composite containing 0.6% of thecommercially available chromi-nuclear complex, FC-804, and 32% of thecommercially available polyacrylic ester emulsion, Rhoplex FRN. Afterimpregnation the sateen swatches were either immediately cured at 110 C.for one hour or simply allowed to air dry at room tempera ture. Therepellency of these treated samples of cotton sateen to stabilized GB istabulated below:

Swatches oven cured Samples air dried after after impregnationimpregnation Age of composite emulsion, days Penetration WettingPenetration Wetting time, time, time, time, seconds seconds secondsseconds (1 day) 5 12, 000 218, 000 9, 000 19, 000

(6 days) 6 10, 000 432, 000 6, 000 20,000

(5 days) 11 10, 000 518, 000 4, 000 23,000

(6 days) 18 7, 000 513, 000 7, 000 10,000

(6 days) As an example of the beneficial effect of mild heating on therepellency obtained in treatments with the composite emulsion, anemulsion identical to that described immediately above was prepared.Portions of this composite emulsion were heated at 40 C. for periods upto 1 hour after mixing and then used for the treatment of swatches ofcotton sateen. All swatches were cured for one hour at C. and thentested with stabilized GB as indicated in table below:

Repellency to stabilized GB Time 0! Swatch No. heating at 40 CPenetration minutes time, Wetting time seconds 0 2,000 24,000 seconds.10 5.000 30 hours. 30 5,000 24 hours. 60 5,000 24 hours.

1 Control.

It is seen that the beneficial effect previously noted on aging of thecomposite emulsion may be greatly accelerated by mild heating for briefperiods prior to impregnation of the textile material.

Example 3 A 10 x 60-inch strip of cotton sateen was impregnated in acomposite emulsion identical to the last emulsion described in Example 2(0.6% FC-804, 32% Rhoplex FRN). The composite emulsion had aged six daysat the time of impregnation of this strip. The strip was padded afterimpregnation so as to give a dry-pick-up of 51 percent by weight. Afterpadding, the strip Was allowed to air dry and was then cured at 110 C.for one hour. The repellency of this strip of treated sateen tostabilized GB was very high; penetration time varied from 7,000 to27,000 seconds, and wetting time was in excess of 5 days. The physicalproperties of this strip of treated sateen are tabulated below:

Air permeability is approximately doubled while abrasion resistance isincreased about 50-fold.

Example 4 Samples of 8.5 oz. cotton sateen were impregnated withcomposite emulsions containing the commercially available chromi-nuclearcomplex of perfluoro-octanoic (FC- 8 804) and the below indicatedpolymeric materials, some stituent of the composite emulsion is anon-ionic acrylic of which are available under the indicated tradenames, ester polymer emulsion. and then cured for one hour at 110 C. 3.The process of claim 1 in which the polymeric con Repelleucy to stab. GEPolymer FC-SO! Dry- Commercial name Polymer type solids, solids, pickup,percent percent percent Penetra- Wetting tion time, time,

seconds seconds Polyco 505 Polyvinyl acetate 44 0.0 97 20,000 21,000 5,000 15. 000 Rhoplex WN-75 do 44 0. 6 7s 20, 000 21, 000 4 5,000 0.000Dare: XssL- do 44 0. 6 68 10,000 15, 000 (Lab. prep.) Polyethylacrylate12.3 0.6 18 1, 500 9,000

l Emulslfied with a polyethylene glycol alkyl ether.

Example 5 stituent of the composite emulsion is a non-ionic, vinyiChromi-nuclear complexes were prepared according to acetate polymercmulslop' Example 1 of US. Patent 2,544,666 in which the acido 20 Theprocess of cialm 1 the lljlolymenc 6011' group consisted essentially ofperfluorobutyric acid and i of the composmaf emuislon polyet aciylate'perfiuorodecanoic acid. These two chromi-nuclear comhe.process of m w ic rpml'liuclear plexes were isolated at 30-35% solutions in isopropanol.ig mccrporaied m t 6 2 3? 15 m Whlch Sutficient of each chromi-nuclearconcentrate was taken ig i consists 655mm y 0 per uoro'octanoy to givecomposite emulsions with Rhoplex FRN containb ing 0.6% by weight of thechromi-nuclear complex and Tnepmcess of i 1 m whlqh chroml'nuclear 32%by Weight of the acrylic polymer. The composite coinp nwrporafed m heinulsion 1S a product the emulsions of these two Chmmimudear complexeswere acido group of which consists essentially of perfluorodecusedimmediately to impregnate swatches of cotton sateen. anoyl groups Theseswatches, after curing for one hour at 100 G, ex- Theprocess of C 3 1 mwhich chroml'nuclear hibited repellency to stabilized GB as indicated inthe coinplsx mcorporatid m emulslori 1s a product the table below: acidogroup of which consists essentially of perfluorobutyryl groups.

8. A composition for bonding to fabric a Werner-type Remloncv orSwatches chromi-nuclear complex in which the acido-group is sefi immedblected from the class consisting of perfiuoroalkanoyl Chmmmudw comm atly groups and w-hydrofiuoroalkanoyl groups containing from 4 to 18carbon atoms, said composition consisting essenlg g ga g s, tially ofwater containing 12-50% by weight of a vinylseconds' sccongis 40 typepolymer in the form of a stable, non-ionic emulsion,

and 0.6 to 3.0% by weight of said chromi-nuclear com- Perfluorodecanoicacid 000 15, 000 p Pcrflu r u wic a id---- 2,000 4,000 9. A stable,aqueous phase composition containing a Werner-type chrcmi-nuclearcomplex, the acido group of which consists essentially ofperfluoroalkanoyl groups After the emulsions above had aged for 6 daysat room containing 8-10 carbon atoms, suitable for applicationtemperature (ZS-30 C.), they were again used to imon acid sensitivematerials without inducing excessive acid pregnate swatches of cottonsateen. The swatches were induced degradation, consisting essentially ofwater concured for 1 hour at 110 C. The penetration time for taining3035% by weight of an acrylic ester polymer in the decanoic acidcomplex-treated fabric had increased to the form of a stable, non-ionicemulsion, and 0.4 to 0.8% 16,500 seconds and the wetting time to 48hours. For by weight of said chromi-nuclear complex. the swatch treatedwith the aged butyric acid complex 10. A method of making a compositionfor impregnatemulsion the penetration time had increased to 5000 sccingfabric, comprising mixing a Werner-type chromi-nuends and the wettingtime to 6000 seconds. clear complex, selected from the group consistingof com- We claim: plexes in which the acido group consists essentiallyof per- 1. A process of rendering a textile fabric highlyresistfluoroalkanoyl groups containing from 4 to 18 carbon ant topenetration and wetting by liquid chemical warfare atoms and complexesin which the acido group consists esagenis, Particularly 0f theG-SBTiBS, Comprising; imllfegnfltsentially of omega-hydrofiuoroalkanoylgroups containing ing the textile With a Composite, non-10mm, aqueousemlllfrom 4 to 18 carbon atoms, with a non-ionic aqueous SiOIlConsisting essentially of P y emulsion Selected 6-) polymer emulsionconsisting essentially of Water and from from the group Consisting ofPolyacrylate emulsions and 12 to 50 percent by weight of polymerselected from the P l/ y acfitate emulsions, in admixture with aWerllefgroup consisting of polyacrylates and polyvinyl esters, and ypchromi-fluclear wmplex in Which the acido group is heating the resultantmixture at a temperature in the selected from the class consisting ofperfluoroalkanoyl range 40 C. to C. for a period of time in the rangegroups and w-hydrofiuoroalkanoyl groups containing from 5 to18{),mjnutes about 418 carbon atoms, to a dry pick-up of from about 25to 50% by weight; freeing the impregnated textile of References Cited inthe file of this patent excess bath liquor; and drying the wet textileat tem erature and times ranging from about 24 hours at foam UNITEDSTATES PATENTS temperature to 30 to minutes at temperatures of from 702,552,910 Stemman y 1951 about 90 to 120 1 1 einman Sept. 23, 1952 2.The process of claim 1 in which the polymeric con- 2,693,458 Olson 1 4

1. A PROCESS OF RENDERING A TEXTILE FABRIC HIGHLY RESISTANT TOPENETRATION AND WETTING BY LIQUID CHEMICAL WARFARE AGENTS, PARTICULARLYOF THE G-SERIES, COMPRISING; IMPREGNATING THE TEXTILE WITH A COMPOSITE,NON-IONIC, AQUEOUS EMULSION CONSISTING ESSENTIALLY OF A POLYMER EMULSIONSELECTED FROM THE GROUP CONSISTING OF POLYACRYLATE EMULSIONS ANDPOLYVINYL ACETATE EMULSIONS, IN ADMIXTURE WITH A WERNERTYPECHROMI-NUCLEAR COMPLEX IN WHICH THE ACIDO GROUP IS SELECTED FROM THECLASS CONSISTING OF PERFLUOROALKANNOYL GROUPS AND W-HYDROFLUOROALKANOYLGROUPS CONTAINING FROM ABOUT 4-18 CARBON ATOMS, TO A DRY PICK-UP OF FROMABOUT 25 TO 50% BY WEIGHT; FREEING THE IMPREGNATED TEXTILE OF EXCESSBATH LIQOUR; AND DRYING THE WET TEXTILE AT TEMPERATURE AND TIMES RANGINGFROM ABOUT 24 HOURS AT ROOM TEMPERATURE TO 30 TO 90 MINUTES ATTEMPERATURES OF FROM ABOUT 90 TO 120*C.